1. Field of the Invention
The present invention relates to devices for use in dispensing fluids to a fluid system and, more particularly, to a device for evacuating and dispensing a fluid to a system, such as a charging fluid to a refrigeration or air conditioning system.
2. Related Prior Art
In motor vehicle production lines, the vehicle air conditioning system is typically evacuated and filled at a charging port of the system. In order to facilitate the charging of the system, a tool is provided which is moved into engagement with the port and which opens a Schrader valve on the port. The port is alternately subjected to vacuum to substantially eliminate air from the system and subjected to a pressurized charging fluid for filling the system with a refrigerant.
It should be noted that in prior art tools, multiple parts forming the internal valve elements for the tool are stacked together and are held in position by bolts extending between the various valve elements, including bolts extending both in the axial and radial direction relative to the axis of the tool. This can lead to a time consuming overhaul process which can be undesirable in mass production assembly lines. In addition, such prior art tools include an element for actuating a Schrader valve wherein the actuating element is limited in movement toward the Schrader valve. However, the stop for the actuating element is often located on an internal valve element which is displaced from the Schrader valve by several other valve members, i.e., by the multiple parts forming the stacked internal valve elements, such that the combined tolerances of these members can result in a wide variation of travel for the actuating element between different tools. This can have a detrimental effect on the operation of the tool in that the actuating element may in some cases be overextended, resulting in damage to the Schrader valve, or in other cases, the actuating element will not extend to the point of fully opening the Schrader valve and thus limit the flow capacity through the tool.
It is generally desirable in a high volume vehicle production line to provide a fitting which may be quickly attached to the port by an automatic mechanism, and which will also evacuate and fill the system to be charged at a high rate. Accordingly, it is desirable to have a dispensing tool which is of simple and reliable construction in order to insure repeated performance on successive vehicles while minimizing maintenance on the tool. Further, it is desirable to provide a tool which provides for high vacuum and charging fluid flow rates through the tool in order to minimize the amount of time that the tool must remain attached to the vehicle. It is also desirable to have a tool which is easily disassembled and assembled by maintenance workers responsible for maintaining operation of the tool.
In accordance with the present invention, a tool assembly is provided for dispensing fluid to a fluid receiving system having a charging inlet tube, and typically including a Schrader valve for controlling flow of fluids into and out of the fluid receiving system. The tool assembly includes a tool housing having an upper housing half and a lower housing half, and enclosing a plurality of internal valve elements.
The lower housing half includes a lower end, and a clamp assembly is located at the lower end including radially moveable clamp members for coupling the tool assembly to a charging inlet tube for a fluid receiving system. The upper housing half includes an upper end defining a plurality of openings for selectively admitting fluids to an interior portion of the housing, and the plurality of valve elements are assembled in axially slidable engagement with each other within the upper and lower housing halves for controlling flow of fluids through the interior portion of the housing.
In accordance with one aspect of the invention, the upper and lower halves are connected to each other at connector portions of the upper and lower housing halves wherein engagement of the connector portions with each other closes the housing to maintain each of the valve elements in operable relation to other ones of the valve elements.
One of the plurality of valve elements comprises an inner body located in stationary relationship relative to the upper and lower housing halves, and the inner body includes passages for controlling flow of vacuum and a charging fluid, which fluid flows are provided to the assembly through the openings in the upper end of the upper housing half. The inner body defines a cavity for receiving a fluid control poppet, and the fluid control poppet includes a hollow cylindrical portion receiving a cylindrical portion of a vacuum control poppet therein. The fluid control poppet and vacuum control poppet are supported for longitudinal movement in an axial direction relative to the inner body and relative to each other for controlling flow of vacuum and flow of charging fluid through the tool assembly.
The inner body additionally defines a vacuum control air passage for controlling air to an area between the fluid control poppet and vacuum control poppet whereby the vacuum control poppet is actuated for movement to open a vacuum passage to the charging inlet tube.
In one embodiment of the invention, the clamp assembly includes a clamp cylinder having a plurality of radially extending apertures wherein each aperture in the clamp cylinder includes a piston which is radially moveable for biasing respective clamp balls radially inwardly into engagement with the charging inlet tube in order to clamp the assembly to the charging inlet tube. The clamp balls are supported in a charge gate cylinder which is positioned within the clamp assembly. The charge gate cylinder comprises an upper cavity and a lower cavity and a charge gate located between the upper and lower cavities and defining a passage for fluid between the tool housing and the charging inlet tube.
An elongated stem member is supported for longitudinal movement through the tool housing and includes an upper portion and a lower portion. The stem member extends through the vacuum control poppet, and the lower portion of the stem member extends through the charge gate for engagement with a Schrader valve. The stem member includes s shoulder adjacent to the lower portion for engaging against the charge gate for limiting movement of the stem member in a direction from the upper housing half toward the lower housing half. The stem member is actuated for movement by air pressure provided at a stem port located centrally of the upper housing half and applying air pressure to the upper portion of the stem member.